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Thursday, December 19, 2002

Archives of Disease in Childhood

12/19/2002
By Harvey McConnell

Further evidence of an increased risk of sudden infant death syndrome (SIDS) among children of smokers suggests the risk may be due to a slower arousal response as a result of in utero tobacco exposure.

Dr Anne Chang and colleagues at the Department of Respiratory Medicine, Royal Children's Hospital, Herston, Australia, found signs after monitoring the sleep and arousal patterns of 20 infants between the ages of 8 and 12 weeks. The age is the peak for SIDS events among full term infants.

Although many diverse mechanisms have been proposed, a consistent finding is that exposure to tobacco smoke in utero significantly predisposes the infant to succumb to SIDS, the researchers point out.

The researchers monitored 10 infants born to mothers who smoked during pregnancy, and 10 born to mothers who did not smoke. All of the infants were born at term, and none was sick or had been receiving any treatment. Assessment also was made of feeding practices, the smoking habits of both parents, income and employment, and levels of postnatal depression, all factors known to affect the risk of SIDS.

A standardized sequence of audiology stimuli was applied binaurally during a rapid eye movement (REM) and NREM epoch, in a controlled sleep environment--temperature, position, use of a pacifier or noise. Infants were monitored for 10 to 12 hours using complex sleep polysomnography.

Five infants exposed to in utero tobacco smoke did not have behavioural arousal response, whereas all non-smoke exposed infants aroused during NREM. However, the clinicians found no difference in REM sleep, and the groups did not differ in routine overnight complex sleep polysomnography parameters.

Dr Chang and colleagues conclude that previous research has indicated that cigarette smoking by the mother could be implicated in up to 30 percent of SIDS cases. "This study adds to the body of evidence that in utero smoke exposure is detrimental to the infant's neurorespiratory system, which governs arousal."
Archives Of Disease In Childhood 2003; 88: 30-33.